But knowledge was not sufficient--a social bond, a spiritual link of perpetual solidarity was required. And this Marc found in Justice. He had often noticed with what a flash of rebellion a boy, molested in his rights, would exclaim: 'That isn't fair!' Indeed, any act of injustice raises a tempest in the depths of those young minds, and brings them frightful suffering. This is because the idea of justice in them is absolute. Mark turned to good use the candour of equity, the innate need of truth and justice, that one finds in children when life has not yet inclined them to mendacious and iniquitous compromises. By way of Truth towards Justice--such was the road along which he strove to direct his pupils, as often as possible requiring them to judge themselves when they happened to be in fault. If they had told a falsehood, he made them admit the wrong they had done both to their schoolfellows and to themselves. If they were disorderly and delayed lessons, he showed them that they were the first to suffer. At times a culprit spontaneously admitted his offence, thus earning forgiveness. Emulation in equity ended by animating those young people; they learnt to rival one another in frankness. At times, of course, there was trouble, conflict, catastrophe, for all this was only a beginning, and several generations of schoolboys would be needed for schools to become the real abodes of healthy and happy life. Marc, however, rejoiced over the slightest results that he obtained, convinced as he was that if knowledge were primarily essential for all progress, nothing definitive with respect to the happiness of mankind could be achieved without the assistance of the spirit of justice. Why did the _bourgeois_ class, which was the best educated, become rotten so soon? Was it not by reason of its iniquities, its denial of justice, its refusal to restore what it had stolen, to give to the humble and the suffering their legitimate share of the world's good things? Some folk, in condemning education, cited the ignominious downfall of the _bourgeoisie_ as an example, and accused science of producing a multitude of casteless individuals, thereby increasing the sum of evil and tribulation. And yes, so long as the passion for knowledge merely for its own sake should become keener and keener in a social system which was all falsehood and injustice, it would only add to existing ruins. It was necessary that science should tend towards justice, and bring to the future city of fraternity a moral system of liberty and peace.